1. Field of the Invention
This invention relates to a vessel for molten metal comprising a box-like inner vessel having bottom and side walls formed by rigid heat-resistant panels which are sealingly joined together along confronting edge surfaces at the inside corners defined by the bottom and side walls, and a heat insulation covering the outer side of the bottom and side-wall panels of the inner vessel. The invention is directed to the method of making such a vessel.
The vessel according to the invention is particularly useful in a furnace for holding molten metal at a controlled temperature, e.g. in die-casting installations, but it also has other uses.
2. Prior Art
Available on the market are heat-resistant panels which can readily be machined by means of ordinary cutting tools, such as saws, drills and milling cutters, and which, in the grades now available, can endure temperatures of 700.degree.-800.degree. C. and extended periods of contact with molten metal. Such panels have also been used in vessels of the above-defined kind.
A known furnace for holding molten metal at temperatures up to 700.degree.-800.degree. C. includes a vessel of the above-defined kind. In that vessel, the panels forming the bottom and side walls of the inner vessel are secured together by means of self-tapping screws passed through the confronting joint surfaces of the panels and engaging directly the material of the panels. A sealing strip of refractory felt is interposed between the confronting surfaces of the joints (U.S. Pat. No. 4,208,043).
Because the coefficient of thermal expansion of the panels is substantially lower than that of the screws, relative movements of the screws and the surrounding material of the panels are unavoidable. As a consequence of such movements, the screws may gradually lose their hold so that they become unable to clamp the panels together with sufficient force to prevent leakage of metal through the joints.